Reverse brake device



Nov. 8, 1932. c. A. MATsoN REVERSE BRAKE DEVICE Filed Feb. 18, 1929 2Sheets-Sheet Nov. 8, 1932'. c. A. MATsoN REVERSE BRAKE DEVICE Filed Feb.18, 1929 2 Sheets-Sheet 1720er? iai' Patented Nov. 8, 1932 narra: starsimam p CARL A. raA'rson, or LYNNFIELD, MASSACHUSETTS, Assienon To manManson ooiyr;

PANY, OF CNCORD, NE'W HAMPSHIRE, A CQBPOEATON OF NEVI HAMPSHIRE.

REVERSE BRAKE DEVICE Application filed February 18, 1929. SerialN0,.S4G,668.

My kpresent invention relates to braking mechanism and more particularlyto an 1mproved automatic reverse brake or clutch` mechanism forautomobiles or other mechanie cal devices. y Y

In the mechanic arts there are numerous situations in which it isnecessary that machinery or shafting be capable of rotative movement inone direction only in the normal working' of the apparatus, and it hasheretofore been impossible to devise means for automatically preventingany reverse rotation. On the contrary, even in devices where it isessential that the device kbe prevented from a reverse or rotarymovement, it is sometimes necessary, particularly when. a device isbeing set` up or adjusted, that vrotary movement in a reverse directiontake place. At the present time there is no mechanism capable ofperforming such a function and ot which I am` aware.

In the use of thepresent day automobile, a dangerous conditionfrequently arises when it is necessary to stop the vehicle on an inclineand where the usual brakes may or may not hold. Regardless of whethersuch brakes do or do not hold, a serious diiiiculty arises when it isnecessary to start the' vehicle in motion after it has been stopped onan incline and this difficulty becomes all the more serious if thevehicle has been stopped on an incline and where there is considerabletraii'ic in close proximity and to the rear. It the driver of theautomotive vehicle releases the toot brake to accelerate the engineprior to letting in the clutch, the vehicle will invariably roll backand a possible accident through colli sion with other cars may occur.Heretofore the only way in which a car could be started under theconditions outlined above was to set the emergency brake, release thefo-ot brake, accelerate the engine, let in the clutch and gradually letoutI or release the emergency brake. This operation requiresvconsiderable skill and is not always feasible.

I am aware that it has been proposed to put one-way clutches Ionautomobiles for the purpose of preventing reverse movement thereof, butnone of these devices so far as I am aware operated successfully and innone of such devices is it possible to throw out the reverse prevention`mechanism so as to allow a backing up `or movement to the rear ont thevehicle under certain conditions. Thesevconditions 4arise where thevehicle, Jfor eXample,i's parked on an incline and with the front wheelsin such proximity to a high curbing as :to prevent a suliicient amountot torwardmovement on the part of the vehicle to allowthe one-way clutchmechanism to move out of operative position and will also occur where itis desired to back up. by means of the usual ref Verse gear the vehicleto which the device is attached. n Y

ln my present invention l have devised means for obviating theVdifficulties above enumerated and have associated with the propellingshaft or transmission, or both,of the vehicle an automatic reverse brakeor clutch mechanism which vautomatcally sets under normal conditions andwhen the automobile to which it is attachedl moves backward. The reversebrake or clutch mechanism forming the subject matter of my presentinvention may be thrown out of action entirely so as to allow mov-ementof the car to the rear and is so designed as to be thrown intoa'position to be operated when the transmission gearing is thrown intoneutral or in any of the 'forward speeds. i

The object of my invention, therefore, is an improved braking or clutch.mechanism for automobiles and the like. i y ln the accompanying drawingsillustrating a preferred embodiment of my invention,

Fig. l is a side elevation partly in section ot an automobiletransmission gearing and showing oneV form of my inventionin sectionapplied thereto; c i Fig. 2 is `an end elevation of Fig. 1 with the rearcover removed;l

Fig. 3 kis a plan viewA of Fig. 1 Fig. 4 is an endA elevation of tion.;

Fig. 5 is a section onvthe line 5-5 of Fig. 4i, and i Fig. 6 is an endelevation of another modication. f Referring to the drawings,fandparticularly to F igs. l, 2, and 3 inclusive, 10 desiga. modicaf nates atransmission casing provided with the usual 'transmission gearing andhaving rotatably mounted therein and extending through the rear endthereof a transmission shaft 11.

Mounted on the top of the transmission casing is a cover 12 in which ispivotally mounted the control lever 13 for operating the slide rods 14and 15 associated with the change gearing within the casing 10. Attachedto the rear of the transmission casing 10 by bolts 16 is a casing 17open at the rear and provided with a cover 18 that is secured inposition by bolts 19. 'The casing 17 `and cover 18 form an enclosurethat is open at the top and such open top is providedvwith 'a coverplate 2O secured in position by the bolts 21. Secured to the splined endof the transmission shaft 11 by bolt 22 is ay recessed flanged member 23and secured totherea face of the flanged member 23 by bolts 24 and nuts25 is a rearwardly extending coupling member 26, such coupling memberextending through a cylindrical perforation 27 in the cover plate 18.The outer peripheral edge of the flanged coupling member 23 anddesignated bythe numeral 28 forms a clutching surface for bra-ke membersto be hereinafter described.

At ythe bottom of the casing 17 and on either side of the vertical linepassing through the center of the bolt 22, as clearly shown in Fig. 2,are bearing shafts 29 and 30, the outer ends of which are threaded andprovided with nuts 31 which bear on the outer surface of the cover plate18 and hold the shafts rigidly in position. Pivotally mounted on thebearing shaft 29 is the lower end of an arcuate member 32, such memberextending upwardly and partially surrounding the flanged coupling member23. :intermediate the ends of the member 32 is formed a chamber 33 andcommunicating with such chamber is a cylindrical chamber 34. Within thechamber 34 is a fre-ely rotatable hardened cylindrical member 35, whilewithin the chamber 33 is a substantially wedge shaped clutching orbraking member 36. The inner surface of the member 36 is groundcylindrically to engage with the ground cylindrical surface 28 of themember 23 and the outer face of such member 36 is also ground to acylindrical or curved surface, and such outer surface is engaged by thecylindrical roll 35. Fitting over the chambers 33 and 34 so as topositively hold the members 36 and 35 in their respective chambers, is acover plate 37 held in position by a plurality of screws 38.

. Rotatably mounted kon the shaft is an arcuate member 39 havinggenerally the shape of the arcuate member 32 but which differs therefromwith respect to certain details of construction at its top end whichwill be hereinafter described@v This member 39 is also provided with achamber 33 and chamber reseyio' 34 and within such chambers respectivelyare located the duplicates of the substantially wedge shaped member 36and the hardened roll 35, but it will be noted from an inspection ofFig. 2 that such wedge shaped member 36 in the chamber'33 in the member39 has its smaller end upward. Each of the members 32 and 39 areprovided with rearwardly eX- tending posts 40 to which are attached theends of a coil spring 41,'such coil spring tending to bring the upperends of such members 32 and 39 toward each other and, therefore, tobring the inner surface of the wedge shaped members 36 into engagementwith the ground peripheral face 28 of the flange coupling member 23. Thenormal direction of rotation of the transmission shaft 11 and,therefore, of the flanged coupling member 23 is in the direction of thearrow shown in Fig. 2, and in such rotation it will be obvious thatthere is a tendency on the part of the wedge shaped members 36 to rideout of engagement with both the ground peripheral face 28 of the flangedcoupling member 23 and the hardened rolls 35.

The upper end of the vmember 32 is provided with a transverse shaft 24on which is pivotally mounted one end of a latcliing lever 43. The free'end' of such latching lever 43 is provided with a latch 44 whichco-operates with a latch 4,5 formed on the upper end of the member 39.TWhen the flanged coupling member 23 is rotating in the direction of thearrow shown in Fig. 2, the wedge shaped members 36 are forced out oflocking or clutching position and the spring 41 will bring the upperends of the members 32 and 39 toward each other sufficiently for thelatch 44 to engage with the latching member 45. Arranged in the coverplate 2O is a. vertical shaft 46, on which and in engagement with theunder face of the cover 20 is a safety latch device 47 which is providedon its under face and on one end with an enlargement 48 that is normallyin engagement with the upper face of the free end of the latching member43, when such latching lever is in the position shown in Fig. V2, whichis the locking position, and prevents unauthorized separation of thelatch member 44 and latch 45. Pivotally mounted on the latching lever 43is a locking lever 49 adapted toengage with the upper inner end of themember 39, as will be hereinafter described. Fach of the sliding bars 14and 15 are provided with cam faces 50 that are adapted to engage withthe under face of the locking lever 49 and move the same upwardly aboutits pivot so as to free the locking end t iereof from the upper innerend of the member 39 and allow, under such circumstances, the spring 41to function to bring the free ends of the members 32 and 39 toward eachother and into the position shown in Fig. 2.

ln the sliding bar 15 is arranged an upioo wardly. and forwardly.projecting member 5l, and on such member is formed integrally Vtherewitha laterally projecting porti n 52 thatV lies normallypiln front of oneend of the safety latclr4.V The underedge or face of the locking lever43 is provided with a portion 53 that lies .in the path of movement ofthe forward wedge 50 on theslide bar rlhe relation of the forward wedgeor cam surface 50 of the slidingbar l5 with respect to the portion 53 ofthe locking lever 43 and the laterally extending portion 52 kon thelaterally and forwardly extending portion 5i on the lever 15 is suchthat the rear face of the laterally Iprojecting member 52 will engagewith one end of the safety latch 47 so as to move the projection 43thereon out of the path of movement of the locking lever 43 before thecam surface 50 Aengages with the portion 53cn the locking lever 43 tolift the same upwardly and remo-ve the latch member 44 out of engagementwith the latch 45.

The mechanism just described in connection with the slidebar l5, whichis the bar for throwing the reverse gearing in the transmission casingl() into action, makes it poss-ible to move the vehicle to which thedevice is attached rearwardly without the reverse mechanism or clutchoperating to prevent rearward movementand the movement of either of theslide bars 14 and l5 into any of the positions to bring the forwardspeeds of the transmission mechanism into action, releases the lockinglever 49 and brings the lockin g or clutching mechanism again intooperative position.

Assuming that the device above described has been constructed andarranged as shown in Figs. l, 2 and 3 and that the transmission shaft llis rotating in the direction of the arrow shown in Fig. 2, then it willbe obvious that such rotative movement will have a tendency to move thewedging members 36 out of wedging relation with the peripheral face 28of the coupling member 23 and the rolls 35. lf it is assumed now thatthe motor vehicle to which the device is attached is brought to restwith either of the forward speeds in operative position, or with none ofthe forward speeds in operative position, and that such vehicle isbrought to rest on an incline, obviously there will be a tendency on thepart of the vehicle to roll backward, thus rotating the transmissionshaft 1l and coupling member 23 in the reverse direction to thatindicated by the arrow shown in Fig. The members 36 being in engagementith the peripheral face 28 of such coupling l member 23 will be forcedagainst the rolls 35 and the wedging action produced is amply suflicientunder all conditions of service to positively lock the transmissionshaft ll from retrograde movement or a movement in the directionopposite to that of the arrow shown in Fig. 2..; Should, however, it bedesi-red to reverse the vehicle, to which the device is vattached bymeans of the usual reversing mechanism, the operator, by properlymanipulating the ileverv 13, will move the slide bar l5 rearwardly ortothe right, as shown in Fig. l. Under. these circumstances theportion52 of thelaterally and forwardly extending member 5l will engage withone end of the safety latch 47 and lwillv move the portion 48 thereonkout of the up ward path of movement ofthe free end of the. locking lever43. Continued rearward movement of the slide ward cam surface 50.thereof to engage with the portion 5l on the under face of the lockinglever 43 and such lockingL lever 43v will bar l5 will cause .the forberotated in a clockwise direction sol as to v move the member 44 out ofengagement with the member 45, and under these circumstances the'transmission shaft 1l may befmovedv in a direction opposite to thatindicated by the Varrow in Fig. 2. Under thesecircumstances of the lever49 engages with the upper inner face of the member 39, when such memberswill be held apartand prevent any locking action between the rolls 35,wedging members 36 and the peripheral face28 of the c0uA pling member23. Y

eferring now to Fig. 4, wherein is shown a modification of the deviceillustrated in Figs. l, 2 and 3, l have provided in the members 32 and39 substantially `rectangular chambers 53 in each of which is slidablymounted a rocker bed 54, the one in association with the member 32 beingforced downwardly by spring 55, while thev one in association with themember 39 is forced upwardly by a spring 55. Mounted for rockingvmovement on the rocking beds 54 are braking and clutching members 56,`the inner faces thereof being wedge shaped, as indicated at 57 in Fig.5, and such wedgeffaces fit inA a circumferentially arranged wedgegroove 58 formed in the periphery of the coupling member 23. rl`heoperation of thismodication is identical with that of the form shown inFigs. l, 2 and 3 and it is believed that a detailed description ofV suchoperation is ynot necessary. The chambers 53 are covered by operatingwith inthe members 32 and 39. The chambers 6l together lwith theperipheral face 28 of the coupling member 23 forms a wedging ,chamberinto the smaller end vof which the rolls 62 areidriven, should it beattempted to rotate the transmission shaft 1l in a direction opposite tothat indicated by the arrow in Fig. 6, unless, as has been explainedabove with relation to the construction illustrated in Figs. l, 2 and 3,the locking mechanism spurposely thrown out of action by the reverseslide bar l5.

Various other forms of my invention will suggestzthemselves to thoseskilled in the art and l do not wish to be limited other than as pointedout in the` appended claims.V

`Having thus described my invention what l claim as new is: l v

l. ln a device of the kind described, the combination of a shaft, amember Xed thereto and rotatable therewith, a freely pivoted memberpartially surrounding the first said member and having a chamber formedtherein, and a wedging device in said chamber normally opere ble tovengage said rotatable member to prevent rotative movement thereof inone direction only.

2. In a device of the hind described, the combination of a rotatablemember, a pivotally mounted member associated therewith and providedwith a chamber, a rotatably mounted roll in said chamber, a wedgingdevice normally in engagement with the roll and with the rotativemember, and yielding means for holding the roll, wedging member androtatable member in engagement with each other. 3. In a device of thekind described, the combination of a rotatable member, a pivotallymounted member associated therewith and provided with a chamber, arotatable roll associated with said chamber, a wedging member located insaid chamber and normally engaging with the rotatable roll and with thef rotating member, said wedging member-so positioned in the chamber asto permit rotative movement of the rotatable member in one directiononly, and means for yieldingly holding the wedging member in engagementwith the rotatable roll and rotatable member simultaneously.

4. In a. device of the kind described, the combination of a rotatablemember, a pair of freely pivoted members associated therewith andpartiallysurrounding the rotatable member, a. wedging device associatedwith each pivotally mounted member and normally in engagement with therotatable member and so positioned as to permit rotative movement of therotatable member in one direction only, means for yieldingly holding thewedging. members in engagement with the rotatable member, and meansassociated with the rotatable Vmember for throwing the wedging membersout of action, whereby rotative movement a springbi in a passage 65 ofthe rotatablemember inthe reverse direction is permitted.

5. In a device of the kind described, the combination of a rotatablemember, pivotally mounted members associated therewith and partiallysurrounding the rotatable member, wedging members slidably mountedv inthe pivoted members, said wedging members being normally in engagementwith the rotatable member, means for yieldingly holding the wedgingmembers in Vengagement with the rotat-` able member, means associatedwith the rotatable member for placing the wedging members in inoperativeposition, and means associated with the pivoted members for maintainingthe wedging members out of wedO-ing position at will.

ln a device of the kind described, the combination of a shaft, a memberfixed thereto and rotatable therewith, a fr-eely pivoted memberassociated therewith and having a chamber formed therein, and a. wedgingdevice of less length than said chamber slidable therein and normallyoperable to engage said r tatabie member to prevent rotative movementthereof in one direction only.

"i". In a device of the kind described, a rotatable member, a pair ofpivotally mounted members partially surrounding the rotatable member,the pivot point of said members being at one side ofthe center of .saidrotatable member, a wedging device associated with each pivotallymounted member and so positioned as to permit rotative movement of therotatable member in one direction only, and resilient means aiiiiied tosaidpivoted members at the opposite side of the center of said rotatablemember to normally draw the free ends of said pivoted members towardeach other.

8. ln a device of the kind described, a rotatable member, a pair ofpivotally mounted members partially surrounding the rotatable member,the pivot point of said members being at one side of the center of saidrotatable member, a wedgingv device associated with each pivotallymounted member and so positioned as Ato permit rotative movement of therotatable member in one direction only, and resilient means affixed tosaid pivoted mem ers at the opposite side of the center of saidrotatable member and adj accnt to the free ends of said pivotedmembersto normally draw the free ends of said pivoted members towardeach other.

. `9. ln a device of the kind described, a rotatable member,a pair ofpivotally mounted members partially surrounding the rotatable member,the pivot point of said membersbeing at one side of the center of saidrotatable member, a wedging device associated with each pivotallymounted memberandv so positioned as to permitrotative movement of therotatable member in one direction only, resilient means afxed to saidpivoted members the free ends of at the opposite side of thecenter ofsaid rotatableV member to normally draw the free ends of other, andcooperating latch members carried by the free ends of the pivotedmembers to hold the free ends oi" said pivoted members in lockedposition. p e

l0. Inav device of the kind described, a rotatable'membcr, a pair ofpivotally mounted members partially surrounding theV rotatable member,the pivot point of said membars being at one side of the center ot saidrotatable member, a Wedging device associated With each pivotallymounted member and so positioned as to permit rotativemovement of therotatable member in one direction only, resilient means afiixed to saidpivoted members at the opposite sideofthe center of said rotatablemember to normally dranT the free ends of said pivoted members towardeach other, cooperating latch members car ried bythe free ends or. thepivoted members to holdV the treev ends of said pivoted members inlocked position, and means to engage one of said latch members to retain`said latch members in their locked engagement.`

l1. In a device of the kind described,a rotatable member, a pair ofpivotally mounted members partially surrounding the rotatable member,the pivot pointof said members being at one side of the center of saidrotatable member, a Wedging device associated with each pivotallymounted member and so positioned as to permit rotative movement oi' therotatable member in one direction only,.re silient means aiiixed to saidpivotedmembers at the opposite side of the center of said rotatablememberto normally draw the Vtree ends of said pivoted members towardveach other, cooperating latch members carried by the pivoted members tohold the free ends of said pivoted members in locked position, means toengage one of said latch members to retain said latch members l in"their locked engagement, and means to release said latch ment.

12. In a device of the kind described, a rotatable member, a pair ofpivotally mounted members partially surrounding the rotatable member,the pivot point of said members being at one side of the center of saidrotatable member, a Wedging device associated With each pivotallymounted member and so positioned as to permit rotative movement of therotatable member in one direction only, resilient means aiiiXed to saidpivoted members at the opposite side of the center of said rotatablemember to normally draw the free ends of said pivoted members towardeach other, cooperating latch members carried by the free ends of thepivoted members to hold the free ends of said pivoted members in lockedposition, means to engage one of said latch members to retain said latchmemmembers from locked engage- 'said pivoted members toward each-tatable member, a

bers in their locked engagement, and cam op erated means to release saidlatch membersfrom locked engagement. Y

13. In a device of the kind described, aro.` tatable member, a pair ofpivotally mountedv members partially surrounding the rotatable member,the pivot point of said' members beA ing at one side of the center ofsaid rotatable member, a Wedging device associated with; each pivotallymounted member and so ypo-z siticned, as to permit the rotatable memberin one direction only, resilient means aiixed to said pivoted mei bersat the opposite side of the center of said rotatable member to normallydraw the freel ends of said pivoted members toward each other, andamember, associated With oneotl said pivoted members to hold said pivotedmembers in unlocked position. Y 14C. Ina device, of the kind described,aropair of pivotally mounted members partially surrounding the rotatablemember, the pivot point of said members vbel ing at oneside of thecenter of said rotatable' member, a `vvedging device4 ,associatedV witheach pivotally-mounted member and so positioned as to permit rotativeymovement of the rotatable member in one direction only, re,-` silientmeans aiiiXed to said pivoted members at the opposite side of the centerof said rotatable member to normally draw:f the -free ends `of saidpivoted members tovvardeach other, a latch associated With one of 4saidvpivoted members to hold said pivoted members in unlocked position,and'means to release said latch whereby the ends of said piv-Y otedmembers may be drawn together bysaid resilient means. c f

15. In afdevice of the kinddescribed, a ro-r tatable member, a pair ofpivotally mounted members partially surrounding the rotatable member,the pivot point of said members being at one side of the center of saidlrotatable member, a. Wedging device associated With each pivotallymounted member and so posi-` tioned as to permit rotative movement ofthe rotatable member in one direction only, and resilient means aiiiXedto said pivoted members at the opposite side ofthe center of saidrotatable member to normally draws7 the free ends ofV said pivotedmembers toward each other, a latch pivotally Vmounted adjacent to theend of one of said pivoted members, a latch ,portion on the pivotedmember Vadapted to be engagedl by said latch to retain said pivotedmembers vin* locked position. f

16. In a device of the kind described, a rotatable member, a pair ofpivotally mounted members partially surrounding .the rotatable member,the pivot point of said members being at one side of the center of saidrotatable member, a vvedging device associated with each pivotallymounted member and so positioned as topermit rotative rotativemovementof.;

free endofthe other 120,

. the other pivoted gaged by said latch to retain said pivoted otedmember adapted movement of the rotatable member in one direction only,resilient means aliixed to said pivoted members at the opposite side ofthe ,I center of said rotatable member to normally draw the free ends ofsaid pivoted members toward each other, a latch pivotally mountedadjacent to the end of one ci said pivoted members, a latch portion onthe free end ot member adapted to be enmembers in locked position, andmeans engaging said latch to hold same in locked position. Y

17. In a device of the kind described, a rotatable member, a pair ofpivotally mounted members partiallyT surrounding the rotatable member,the pivot point of said members being at one side of the center of saidrotatable member, a Wedging device associated With each pivotallymounted member and so positioned as to permit rotatable member in onedirection only, re-

silient means affixed to said pivotedmembersv at theopposite side of thecenter of said rotatable member to normally draw the free ends of saidpivoted members toivardeach other, a latch pivotally mounted adjacent tothe end 'of one ot said pivoted members, a latch port-ion on the treeend of the other pivto be engaged by said latch to retain said pivotedmembers in locked position, and a second latch pivotally mounted on saidfirst latch and adapted to en- A gage the free end of the other pivotedmember to hold said pivoted members in unlocked position.

18. In a device of the kind described, a rotatable member, a pair ofpivotally mounted members partially surrounding the rotatable member,the 'pivot point of said members being at one side of the cen-er of saidrotatable member, a wedging device associated `With f each pivotallymounted member and 'so posiposition,

tioned as to permit rotative movement/of the rotatable member in onedirection only, resilient means afiXed to said pivoted members at'theopposite side ot the center of saidv rotatable member to normally drawthe freeV ends ot said pivoted members toward each other, a latchpivotally mounted adjacent to the end of one of said pivoted members,V alatch portion on the' reeend of the other pivoted member adapted to beengaged by said latch to retain said pivoted members in locked meansengaging said latch to hold same in locked position, and means torelease said latch engaging means. y

. 19. In a device of the kind described, a rotatable member, a pair ofpivotally mounted members partially surrounding the rotatable member,the pivot point of said members being at one side of the center of saidrotatable member,A a Wedging device associated With each pivotallymounted member and so positioned as to permit rotative movement of therotative movement of the rotatable member in one direction only,resilient means affixed to said pivoted members at the opposite side ofthe center of said rotatable inember to normally draw the free ends ofsaid pivoted members toward each other, a latch pivotally mountedadjacent to the end ot oneA of said pivoted members, a latch p0rtion onthe Jfree end of the other pivoted inember adapted to be engaged by saidlatch to retain said pivoted members in locked position, means engagingsaid latch to hold same in locked position, and cam operated means torelease said latch engaging means.

20. In a device of the kind described, a ro-A tatable member having acircumferential V -shaped groove therein, a pair ofpivotally mountedmembers partially surrounding the rotatable member, the pivot point ofsaid members being at one side of the center 'of said rota-table member,a vvedging deviceassocia-ted vvith each pivotally mounted member and sopositioned as to permit rotative movement of the rotatable member in.one direction only, said Wedging device having a portion adapted toseat in said V-shaped groove.

21. In aI device ot the'kinddescribed, the combination of a rotatablemember, a pivotally mounted member associatedl therewith andprovidedwith a chamber, said pivoted member being also provided with arecess communicating with said chamber, a rotatable roll in saidirecess,and a wedging device in said chamber normally iii engagement With theroll and with the rotative member.

22.*In a device of the kind described, the t combination of a rotatablemember, a pivotally mounted member associated therewith and providedwith a chamber, said pivoted member being also provided` with a recesscommunicating with said chamber, a rotatn able roll in said recess, aWedging devicein said chamber normally in engagement With the roll andwith the rotative member,'and yielding means :tor holding the roll,ivedging member, and rotatable member in engagement With each other.

In testimony whereof, I have signed my name tol this specification.

CARL a. MATsoN. I

izo

